On the one hand, the people who can reverse engineer stuff got too good: either they got tired of it, or they're getting paid big bucks to do it professionally. On the other, (perhaps this is jaded) new programmers are just learning scripting/web technologies and never peel back the covers of how the system actually works.

Perhaps reverse engineering proprietary products should be a mandatory tour of duty for young programmers, like military service in some countries. :)

Google play store APIs and protocols ARE being reverse engineered and re implemented.

I run microG with store apps with no issues with everything I have tried.

Doing it to a chat-app has an obvious benefit: you can use your own application with your custom UX, and connect it with multiple networks at once, or multiple accounts at the same time on the same network.

Doing it with something like Airdrop is kind of a nebulous proposal. If you want to share files with someone next to you, and for some reason you hate Airdrop, then there's lots of other alternatives. Reverse engineering Airdrop gets you nothing special.